The present invention is directed to implantation of artificial joint components and in particular to acetabular joint components. More particularly, it relates to an instrument for reaming the acetabular socket which allows the connection of and removal of acetabular reamer cutting heads and the application of force to the reamer head mounted on an angled reamer housing. While the instrument is described in connection with an acetabular reamer, it should be noted that the reamer disclosed can be used with other joints. In the case of a reamer, there is typically a drive shaft located within the instrument housing for rotating the reamer cutting head.
Total hip replacement or arthroplasty operations have been performed to repair the acetabulum and the region surrounding it and to replace the hip components such as the natural femoral head and acetabular socket which have degenerated.
With regard to the acetabulum, many instruments have been designed to locate either the acetabular cup or provide reamers for repairing the acetabulum to receive such a prosthetic cup. Such instruments are shown in U.S. Pat. Nos. 4,305,394, 4,632,111, 5,037,424, 5,061,270, 5,320,625, and 6,395,005.
In addition, there have been various designs for the acetabular reamers themselves, including the reamer and holder shown in U.S. Pat. No. 5,658,290. A similar reamer is shown in U.S. Publication No. 2005/0124981 along with a holder for the same. While these patents show holders for mounting the reamer via a drive shaft to a power source, it has been found that an improved force application system that reduces torque applied to the reamer head and handle from the motor driving the drive shaft for the reamer head is desirable.
In general, such instruments include a shank or handle portion which has a hollow housing which houses a rotatable drive system. The handle housing leading end includes a quick disconnect for coupling, for example, an acetabular cutting reamer having a hemispherical cutting surface and a coupling system on the acetabular reamer preferably having four rods, bars, or other coupling elements extending from a central hub area preferably located adjacent the equator of the hemispherical cutting surface. Of course the hub could be eliminated with the bars extending continuously across the reamer and the rods or bars could be recessed within the reamer cavity.
Generally orthopedic reaming, including acetabular reaming, utilizes a series of reamers which increase in size in one or two millimeter steps. These reamers are used in series to enlarge an opening for the receipt of a prosthetic implantation. Incremental reamers are required because excessive heat is generated if the surgeon tries to remove too much tissue or bone with a single reamer. In addition, surgeons may wish to remove the reamer either in the wound or outside thereof to verify the size, bone condition, and implant orientation. Because of this the surgeon must be able to connect and disconnect the reaming tool from the holder preferably in a simple, easy step, and replace a first reamer with a second reamer positively and quickly.
Currently, acetabular reamers such as shown in U.S. Patent Publication No. 2004/0172036 and U.S. Pat. Nos. 8,282,639 and 8,348,959 show reamer handles having a connector at the end opposite the reaming head which connector is adapted to connect to a drive motor. The drive motor may be an electric motor or a pneumatic motor. It can be seen with the above reamers that one must hold the drive motor and the handle drive system or housing of the acetabular reamer to prevent relative rotation therebetween. This requires the surgeon use both hands to prevent relative rotation between the motor and housing when reaming the acetabulum.